# C Program to Find the Sum of Natural Numbers using Recursion

This post helps us to find the sum of natural numbers using recursion using C programming.

## C Program to Find the Sum of Natural Numbers using Recursion

```#include<stdio.h>
int recusum(int s);
int main()
{
int num;
printf("Enter a positive number:");
scanf("%d",&num);
printf("sum=%d",recusum(num));
return 0;
}
//function calling process
int recusum(int s)
{
if(s!=0)
return s+recusum(s-1);
else
return s;
}```

## Explanation

This C program uses the recursion function, its the process of repeating items in a self-similar way, in simple words function calls itself. In this program, we initialize a function namely recusum(int s), and in the main function, we iterate a variable named num.

```int recusum(int s);
int main()
{
int num;
printf("Enter a positive number:");
scanf("%d",&num);
printf("sum=%d",recusum(num));
return 0;
}```

The function is called for the calculation and to get the desired result. Using the if-else condition we calculate the recursion value of the number entered by the user.

```//function calling process
int recusum(int s)
{
if(s!=0)
return s+recusum(s-1);
else
return s;
}```

After the calculation part. we have now obtained the desired output. 